Automotive lift systems have been long known in the art. However, during approximately the last fifteen years, the primary system used to perform maintenance and service upon and from underneath of automotive vehicles has changed from an in-ground post lift system to a so-called on-ground system.
One reason for a ground level system lies in its environmental advantages. More particularly, the U.S. Environmental Protection Agency (EPA) and the U.S. Occupational Safety and Hazards Agency (OSHA) have imposed strict and costly regulations relating to most forms of on-site excavation that include the use or storage of toxic chemicals in the ground. In the prior art of in-ground post-lift systems, it was necessary to store hydraulic, and other potentially hazardous materials, underground. Accordingly, and primarily as a response to such governmental regulation, the trend in the last fifteen years has been strongly away from in-ground post lift systems and in the direction of above-ground lift systems.
Among the latter category, a type of lift known as the parallelogram lift has appeared. The term parallelogram is employed because, when viewed from the side, the profile of the structure exhibits the configuration of a parallelogram. This style of lift is unique in the above-ground market in that it has eliminated the need for central posts. Such posts are undesirable in that they consume room and create potential obstruction to workers. Therefore, the elimination of posts has brought about a saving of space and provided enhanced efficiency over prior art in-ground systems. However, the parallelogram lift has encountered market resistance in the United States due to reasons of its newness of design and concerns in respect to its safety, notwithstanding the fact that the parallelogram-style lift is, by most analyses, the safest lift manufactured today. Another factor is that existing parallelogram systems make use of longitudinal on-ground base elements between the lifting legs which inhibit left-to-right and front-to-back access to the vehicle. Also, a prior art parallelogram lift, upon closure during descent, is capable of cutting hoses and cords in the work area.
That prior art most representative of such parallelogram automotive lift systems known to the inventor comprises the following:
U.S. Pat. No. 3,330,381 (1967) to Halstead, entitled Vehicle Lift; U.S. Pat. No. 4,447,042 (1984) to Maiser, entitled Vehicle Lift; and U.S. Pat. No. 4,848,732 (1989) to Rossato, entitled Lifting Ramp.
With respect to the system hydraulics, the prior art is represented by U.S. Pat. No. 2,764,869 to Scherr which teaches a primitive, mechanical fluid control of a generally related hydraulic circuit. Such a system cannot provide the precision or durability required in the present application.
It is therefore a goal of the present invention to effect the elimination of baseframes, that is, cross-connecting or cross-coupling elements between left and right, and front and back, rows of hydraulic lifting legs that are used in existing parallelogram lifts, and which impede front-to-rear and right-to left access to the elevated vehicle.